<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>if语句练习</title>
		<script type="text/javascript">
			var score = prompt("请输入小明的成绩");
			// alert(score);
			if( score > 100 || score <= 0 || isNaN(score)){
				document.write("错误")
			}else{
				if( score <= 60 )
					document.write("吃席")
				else if(score <= 70 )
					document.write("吃饭")
				else if(score <= 80 )
					document.write("吃菜")
				else if(score <= 90 )
					document.write("吃肉")
				else if(score <= 100 )
					document.write("想吃啥吃啥")	
			}
		</script>
	</head>
	<body>
	</body>
</html>
